1. Field of the Invention
The present invention relates to Compact Peripheral Component Interconnect (xe2x80x9cCPCIxe2x80x9d) computer systems. More particularly, the present invention relates to providing reliable card detection in a CPCI system.
2. Description of Related Art
CPCI is a high performance industrial bus based on the standard PCI electrical specification in rugged 3U or 6U Eurocard packaging. CPCI is intended for application in telecommunications, computer telephony, real-time machine control, industrial automation, real-time data acquisition, instrumentation, military systems or any other application requiring high speed computing, modular and robust packaging design, and long term manufacturer support. Because of its extremely high speed and bandwidth, the CPCI bus is particularly well suited for many high-speed data communication applications such as servers, routers, converters, and switches.
Compared to standard desktop PCI, CPCI supports twice as many PCI slots (8 versus 4) and offers a packaging scheme that is much better suited for use in industrial applications. Conventional CPCI cards are designed for front loading and removal from a card cage. The cards are firmly held in position by their connector, card guides on both sides, and a faceplate that solidly screws into the card cage. Cards are mounted vertically allowing for natural or forced air convection for cooling. Also, the pin-and-socket connector of the CPCI card is significantly more reliable and has better shock and vibration characteristics than the card edge connector of the standard PCI cards.
Conventional CPCI defines a backplane environment that is limited to eight slots. More specifically, the bus segment of the conventional CPCI system is limited to eight slots, which includes a system slot and peripheral slots. The system slot provides the clocking, arbitration, configuration, and interrupt processing for up to seven peripheral slots.
The newest trend in CPCI systems is to support hot swappable front cards. Hot swappability is the ability to unplug and plug a card while the system remains on. In other words, hot swappability is the ability to exchange cards while the system is running so that there is no need to reboot the system. The CPCI Hot Swap/HA specification defines, among other things, that the connector-pin P1-D15 (in the backplane) and connector-pin J1-D15 (in the front card) be designated as a BD_SELECT# line. The BD_SELECT# line is used to detect the insertion of a hot swappable front card into a slot of the backplane, and to allow the powering-up/down of the card by the hot swap controller. The specification further defines the dynamic interface protocol between the system""s hot swap controller and the card through this line. However, if a non-hot swappable front card, which is non-compliant to the Hot Swap/HA Specification, is inserted in a slot of the backplane, the hot swap controller in the conventional system would not know of the insertion of the non-compliant front card. In other words, the conventional hot swap controller cannot detect the presence of non-hot swappable front cards so that an accurate hardware configuration would not be known to the operating system if non-hot swappable front cards were present.
Accordingly, it would be advantageous to provide a CPCI system that can reliably detect the insertion of all front cards, whether hot swappable or not.
The present invention relates to providing a CPCI system that is adapted to reliably detect the presence of all front cards, whether hot swappable or not. The reliable detection of all front cards provides the operating system with a more accurate view of the hardware configuration.
The present invention has a line that is used to detect the presence of a front card. The line is connected to a connector-pin in a connector of a slot. The line is also connected to a pull-up resistor so that when a front card is not inserted in the slot, the line has a high value. When a front card is inserted in the slot, the connector-pin mates with a corresponding connector-pin in the front card. Note that the corresponding connector-pin is connected to a ground layer of the front card so that the line becomes grounded. The voltage level on the line is input to a register that outputs a high or low to a circuit for detecting the presence of a front card. The circuit may be a hot swap controller, a CPU or a status indicator. Accordingly, depending on the output of the register, the circuit determines whether a front card is present in the particular slot.
An embodiment of the invention includes a computer system including a circuit board, with the system comprising a slot coupled to a front side of the circuit board. A plurality of connectors is affixed to the circuit board in alignment with the slot, with the plurality of connectors including a first connector. A plurality of connector-pins are extended in a direction substantially perpendicular to and away from the circuit board, and has a column and row arrangement within the connectors. The first connector includes first and second connector-pins. A register having an input line and an output line is provided, with the input line connected to a voltage source through a pull-up resistor, and the first connector-pin connected to the input line of the register. A circuit having an input terminal is connected to the first connector-pin through the register, with the register connected to the input terminal of the circuit via the output line of the register, wherein depending on a voltage level of the first connector-pin, the register transmits one of a high and low signal to the input terminal of the circuit whereby the circuit detects a presence of a front card in the slot based on said one of a high and low signal.
Another embodiment of the invention includes a circuit board having a front side, with the circuit board comprising a plurality of slots coupled to the front side of the circuit board. A plurality of connectors is disposed within each of the plurality of slots and including a first connector in each of the slots, with the respective first connectors of the slots including a first connector-pin and a second connector-pin. A plurality of connector-pins is disposed in an arrangement of a plurality of columns and rows in each of the connectors, with the plurality of columns including first and second columns. The connector-pins in the first and second columns are connected to a ground layer of the circuit board, except for the first connector-pins in the first connectors. An input/output device has a plurality of input lines and output lines, each of the input lines are connected to a voltage source through a pull-up resistor, and the first connector-pins in each of the slots are connected to the input/output device via the respective input lines. A circuit has a plurality of input terminals and is connected to the first connector-pins through the input/output device. The input terminals of the circuit are connected to the output lines of the input/output device, wherein depending on voltage levels of the respective first connector-pins, the input/output device transmits respective signals to the corresponding input terminals of the circuit whereby the circuit detects a presence of a front card in corresponding ones of the slots depending on the respective signals.
A more complete understanding of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.